The present invention relates to a damper disc of a long travel type, i.e., having a large torsion angle, which can be used as a clutch disc of a dry type or a wet type and also can be used as a clutch disc of a lock-up clutch assembled in a torque converter for an automobile and others.
A damper disc of a long travel type has already been disclosed in the Japanese Utility Model Application No. 57-10387 (U.S. Patent Application Ser. No. 421,338). In this known disc, a hub flange means is divided into an inner flange and an outer flange. Both flanges are circumferentially connected by spring, and the outer flange is circumferentially connected to side plate by springs, so that a torsion angle between the inner flange and the side plate becomes larger than that of conventional discs having undivided flanges. However, in the known disc of the long travel type, a hysteresis torque caused by a friction between disc members is set high and constant in any twisted (torsionally turned) position. Therefore, if the disc is used as a clutch disc of a dry type for an automobile, a torque vibration of an engine in an idling driving can not sometimes be absorbed sufficiently and is transmitted to a driving mechanism such as a transmission, so that gear attacking noises may be generated in the driving mechanism.
Accordingly, it is an object of the invention to provide an improved damper disc, overcoming the above-noted disadvantages, which comprises a hub adapted to be connected to an output shaft; circumferentially spaced flanges projecting radially outwardly from the outer periphery of the hub; a pair of side plates connected to a torque input portion, disposed at both sides of the flanges and rotatably fitted around the hub; spacers circumferentially spaced to the flanges; sub-plates rigidly holding the spacers and rotatably fitted around portions of the hub between the side plates and the flanges; a first friction member having a small friction force and disposed between the flange and the sub-plate; a second friction member having a large friction force and disposed between the sub-plate and the side plate; a first spring always circumferentially connecting the flange and the side plates; a second spring adapted to circumferentially connect the flange and the spaces in a second torsion operation in which a relative torsion angle between the flange and the side plates is larger than a predetermined value; and a third spring adapted to connect the spacers and the side plate at least in the second torsion operation.
Other and further objects, features and advantages of the invention will appear more fully from the following description of the preferred embodiments of the invention.